Ego
In Freud's view the ego mediates between the id, the superego, and the external world to balance our primitive drives, our moral ideals and taboos, and the limitations of reality (ego means I in Latin—the original German word Freud applied was "Ich".) Although in his early writings Freud equated the ego with our sense of self, he later began to portray it more as a set of psychic functions such as reality-testing, defense, synthesis of information, intellectual functioning, memory, and the like.